Archival Treasures

The collection of parchments and illuminated as well as sealed documents preserved in the archive is exceptionally rich. They attest to rights and record the conferment of important political and religious offices.
Parchment is a membrane made from animal skin (sheep or cattle), specially treated and also known as vellum. It has been used since ancient times as a precious and durable writing material. Through soaking in an acidic solution, the animal's hair was easily removed, and the skin was stretched on a frame. The side where the hair was removed was usually darker, while the other, the "flesh side," was lighter and more suitable for writing. In particularly valuable books and documents, it is not uncommon to find miniatures or illustrations depicting various subjects and scenes of daily life.
These decorations are very delicate, and the colors used are composed of two parts: the pigment, such as the purple dye obtained from specific Mediterranean mollusks (an organic dye) or the turquoise from lapis lazuli (a true inorganic pigment); and the binder, made up of organic substances that are easily attacked by microorganisms such as bacteria and fungi.
The parchment shown at the top, for example, represents a privilege granted to Simonino Ghiglino, secretary to the Duke of Milan, Filippo Maria Visconti, known as Angelo, and his brother in 1441. On the parchment, the miniature depicting the coat of arms of the Visconti family is still clearly visible: the serpent swallowing a child and the imperial black eagle with lowered wings. The Visconti serpent has been one of the most representative symbols of Milan and the ancient Duchy for over seven hundred years.